The overall goal of this protocol was to evaluate autonomic balance as a function of hostile personality style. We hypothesized that high hostiles would be characterized by reduced parasympathetic nervous system (PNS) antagonism of sympathetic nervous system (SNS) effects on myocardial repolarization. During the course of work on this protocol, we have screened over 350 candidates for inclusion in this study. Of these a total of 55 subjects completed at least one of the three sessions included in this protocol. The major cause of drop-out prior to protocol completion was GI distress due to the neostigmine pretreatment. With respect to the core hypothesis, the findings among the female subjects were consistent with the hypothesized association of high hostility levels with weaker PNS antagonism of SNS effects on myocardial repolarization (indexed by T-wave vector magnitude -- TVM -- attenuation to isoproterenol infusions). Thus, relative to saline pretreatment, atropine pretreatment enhanced TVM decrease during isoproterenol infusion more among low than high hostile women. In contrast, relative to saline pretreatment, PNS enhancement with neostigmine enhanced TVM recovery from isoproterenol infusion more in low than high hostile women. Results from men were less clear, with no effect of atropine on TVM responses and an effect of neostigmine to enhance TVM recovery, but in the low hostile men more than the high hostile men. These findings indicate that high hostile women show decreased PNS antagonism of SNS effects on myocardial repolarization, while in men the picture is less clear. In an ancillary, add-on study under this protocol, we also evaluated in a subset of subjects the effects of the various isoproterenol-pretreatment combinations on the expression of certain early inflammatory genes and cytokines on circulating monocytes in this study.